Yeah, I would go for immediately. If you're fired or anyone is, let them know or understand yourself that the Dept. of Labor WILL represent you. It's their job. They will put him through the ringer. And, if he's any amount of intelligent, he'll know they can yank either his business license or his veterinary license.
I really URGE you to report this and get it dealt with. And hey, if you get a new job during the investigation, you'll get a windfall for all the penalties he could face.